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[EXERCISE ADVISER]

How to Keep Scuba Diving Safe

Mary Ann Everhart-McDonald, MD, MS

THE PHYSICIAN AND SPORTSMEDICINE - VOL 28 - NO. 5 - MAY 2021


As scuba diving grows in popularity, divers must know the safety factors involved. For example, they need to know their abilities and how to dive within those limits, how to react to emergency situations, and how to prevent and treat common medical conditions. Below are clear answers to common questions.

Q. What is swimmer's ear? How do I avoid it?

A. The medical term for this condition is otitis externa. It's an infection caused by bacteria that enter the outer ear and grow in the warm, damp environment often found in divers' ears.

Bacteria have difficulty growing in the external ear canal if it is acidic (has a pH from 4 to 5). Placing an acidic drying solution in the ear for 5 minutes, twice a day—once before the first dive and again at the end of the diving day—may prevent infections.

Pharmacies sell a variety of drying solutions—the label should list 2% acetic acid mixed with 85% isopropyl alcohol. For a home remedy, you can mix equal parts white vinegar and water and then mix this with an equal amount of rubbing (isopropyl) alcohol.

Q. Why do scrapes against coral hurt more and heal slower than scrapes I get on land?

A. Bacteria, debris, and nematocysts (tiny stingers) from coral polyps are a source of infection and irritation to the open wound. In the water, bacteria easily flow into the wound. The best solution is to wash the wound quickly and thoroughly with soap and water. After washing, apply a triple antibiotic cream and do not bandage the wound, or bandage it loosely, allowing air to circulate.

If you were unlucky and came in contact with fire coral (not a true coral but a stinging hydroid), the painful burning sensation is caused by nematocysts. To deactivate them, apply white vinegar (or a 5% acetic acid solution) to the wound until the pain eases. If vinegar is not available, try a paste or powder of baking soda. If neither vinegar nor baking soda is available, rubbing alcohol may be used.

Once the pain lessens, dry the skin, and apply hydrocortisone ointment. If the burning returns, the nematocysts may still be on the skin; scraping the area with a credit card or the edge of a knife may remove them.

Q. What causes seasickness? How do I prevent it?

A. The true cause of seasickness is still being debated. The leading theory involves confusion of signals to the brain, in which the visual system reports little movement of the immediate surroundings but the balance system in the inner ear senses much movement. The conflicting signals can lead to nausea and vomiting.

Plan ahead to prevent seasickness. Prevention is more effective than correcting the symptoms after they occur.

Medications most commonly used to prevent seasickness are dimenhydrinate, meclizine, and a prescription patch containing scopolamine. Divers should test these medications for 24 hours before a dive to identify any adverse reactions such as excessive drowsiness, confusion, or hallucinations that would render divers unfit to dive.

Some people swear by home remedies such as ginger pills or elastic bands that place pressure on the wrist. Little research has been done on these remedies; however, if such aids help, they produce no side effects that would cause problems while diving.

Before boarding the boat, avoid overeating or eating greasy foods, which do not easily digest. Avoid caffeine, which may cause nausea, and avoid drinking alcohol.

Once on board, remain along the center line toward the stern and avoid the upper decks to reduce the sensation of rolling. Focus on an object along the horizon (for example, a cloud or lighthouse) to lessen the conflicting visual signals to the brain.

Q. Why do divers take decongestants? Are they safe?

A. Some divers believe decongestants help them "clear" or equalize the pressure in the sinuses and between the outer ear and middle ear. These medications decrease the swelling of the tissue that lines the sinuses and eustachian tubes, which connect the middle ears to the throat region, thus increasing their size and allowing easier passage of air. The eustachian tubes permit air from the mouth to equalize the air pressure around the eardrums when there is a sudden change in outside pressure, such as during a dive.

The danger of using a decongestant is that the effects of the medicine may wear off while the diver is still under water. As the diver ascends, the air in the middle ear expands as the water pressure decreases. If the eustachian tubes have narrowed, the pressure will be greater in the middle ear than in the outer ear, causing severe ear pain. It may even cause the eardrum to rupture.

Q. Are anti-inflammatory pain medications safe while diving?

A. Yes. Whether these drugs—examples are aspirin, naproxen, ibuprofen, and ketoprofen—are over-the-counter or prescription, they do not interfere with central nervous system functions, which include mental alertness, judgment, and coordination. These medications may be helpful because they relieve the aches that develop when divers overuse their muscles carrying tanks and equipment.

Q. Are narcotic pain medications safe while diving?

A. Potential side effects of these medications are serious for divers. It's best not to take a narcotic medicine and dive. The side effects may include drowsiness, decreased mental alertness, confusion, impaired judgment, and decreased coordination. This group of medicines includes codeine, hydrocodone, and oxycodone. Ask your doctor or pharmacist if you are not sure what is in the medicine you are taking.

Q. What factors may increase my risk of decompression sickness (the "bends")?

A. Most factors are related to poor diving practices and skills:

Rapid ascents without a 3-minute safety stop at 15 feet. As the pressure surrounding the diver lessens during ascent, the nitrogen that has collected in various tissues is released into the blood and is carried to the lungs. A rapid ascent will not allow enough time for the nitrogen to gradually return from the tissues into the blood and then exit with exhaled air. You should ascend no faster than 30 feet per minute. The 3-minute safety stop at 15 feet allows nitrogen to leave the body and prevents bubbles from forming in various tissues.

Diving beyond the training and experience of the diver. A diver who goes deeper than their training level dictates, enters caves, dives in extreme conditions, or uses mixed gases without proper training is taking unnecessary risks. Courses are available nationwide through the Professional Association of Diving Instructors (PADI), National Association of Underwater Instructors (NAUI), and other organizations.

Lack of familiarity with and improper use of equipment. This includes buoyancy controls and air consumption monitors.

Diving outside guidelines for no-decompression stop limits. Dive tables and computers provide safety guidelines that take into account the depth of dive, time spent underwater, and time spent on land between dives to help divers avoid decompression sickness.

Flying too soon after diving. This is similar to ascending too fast from deep water to the surface. Nitrogen leaves various tissues at various rates of speed. If it is still in the tissues, the rapid change in cabin pressure may cause it to form nitrogen bubbles that can block blood vessels or disrupt the function of nerves and muscles.

Other factors that may contribute to decompression sickness include:

Dehydration. This may result from not drinking enough fluids, sweating excessively, or consuming fluids that increase urine output, such as caffeinated drinks or alcohol. Dehydration decreases the amount of blood available for gas exchange and may slow nitrogen removal from the body.

Hypothermia (cold body temperature). This may increase the total amount of nitrogen dissolved in the tissue and decrease blood flow to the extremities, slowing nitrogen removal from the body. Wearing the appropriate dive suit and shortening the exposure time will help avoid this problem.

Obesity. Fat is known to hold a higher amount of dissolved nitrogen than other tissues. Therefore, the more fat a person has, the more nitrogen they retain and the slower the nitrogen is removed.

Lack of fitness. Physical fitness decreases body fat and improves a diver's tolerance to exertion. Overexertion can cause fatigue or hyperventilation (breathing too fast). Both situations are uncomfortable and may put a diver in danger.


For More Information

Diving can be a safe, fun experience. An excellent resource for further answers to diving questions is the Divers Alert Network (DAN), phone: (919) 684-2948; available from 9 am to 4 pm EST.


Remember: This information is not intended as a substitute for medical treatment. Before starting an exercise program, consult a physician.

Dr Everhart-McDonald is in private practice in physical medicine and rehabilitation in Columbus, Ohio.


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